Method for making elastic bands



Feb. 19, 1957 Filed July 18, 1952 W. H. SPENCER METHOD FOR MAKINGELASTIC BANDS 3 Sheets-Sheet 1 INVENTOR; WILLIAM H. SPENCER ATTORNEYFeb. 19, 1957 w. H. SPENCER 50 METHOD FOR MAKING ELASTIC BANDS FiledJuly 18, 1952 3 Sheets-Sheet 2 INVENTOR. WILLIAM H. SPENCER ATTORNEY w.H. SPENCER 2,781,550

METHOD FOR MAKING ELASTIC BANDS Feb. 19, 1957 Filed July 18, 1952 3Sheets-Sheet 3 FIG. 5

INVENTOR.

WILLIAM H. SPENCER ATTORNEY METHOD FOR MAKING ELASTIC BANDS William H.Spencer, Alliance, Ohio Application July 18, 1952, Serial No. 299,549

Claims. (Cl. 1853) This invention relates to a method for manufacturingtubing of vulcanizable material, and particularly tubing for productionof full-circle seamless elastic bands. I

Heretofore, full-circle rubber bandshave been produced by providing atube of unvulcanized rubber by known extrusion methods, applying theextruded tube oven a mandrel, placing the mandrel in open steam of avulcanizer at about 190 F. for a vulcanizing cycle, re-

moving the mandrel from the vulcanizer, removing the rubber tube fromthe mandrel, and cutting the tube into narrow bands of vulcanizedrubber. This method, generally, has a serious disadvantage that it hasbeen diflicult to expand or mount the unvulcanized tubing onto themandrel, and to remove the vulcanized tubing from the mandrel. Tubingmounted on a mandrel of relatively smaller diameter than the tubing hasbeen objectionable because sagging of the tubing caused the elasticbands to be elongated or ovate instead of circular; moisturecondensation on the inner surface of the tubing, from the vulcanizingsteam ostensibly had a tendency to weaken the elastic bands; andover-curing at the points of contact of the tubing with the mandrel,usually metal, had a similar, tendency to weakenjthe elastic bands atsaid points of contact. a

One object of the present invention is to provide a method by which theunvulcanized, extruded tubing of rubber-like material is easily mountedon a mandrel of relatively smaller diameter, and wherein the tube ismaintained truly circular during the vulcanization process.

Another object of the invention is to provide a method of the characterdescribed wherein localized metal to rubber contact and condensation ofmoisture are obviated, whereby the elastic bands produced will be ofsubstantially uniform elasticity and strength throughout.

Other objects of the invention will be manifest from the following briefdescription and the accompanying drawings:

Of the accompanying drawings: Figure-1 is a side elevation, partly incross-section, illustrating an open steam type vulcanizer utilized inconnection with the invention Figure 2 is a diagrammatic illustration ofa portion of the apparatus used in practicing invention. y

Figure? is a perspective view of a full-circlerubber band made by saidmethod. I 1 T Figure 4 is an enlarged vertical cross-section takenlongitudinally through the vulcanizer of Figure 1, and

the method of the illustrating the improved vulcanizing apparatus.

Figure -5 is a cross-section, on the same scale, taken nited StatesPatent 0 2,781,550 Patented Feb. 19, 1957 reel 17 having a central shaft18 journalled in bearings 19 and 20 at the upper ends of spaced uprights21 and 22 on the truck, whereby the reel is rotatable about a horizontalaxis. Shaft 18 has a rounded end portion 18a engageable with a stopblock 23 on the inner face of door 11, when a clutch part 24 fixed onthe other end of the shaft is in clutching engagement with acomplemental clutch part 25 on the axially aligned end of a driven shaft26 journal-led in a bearing 27 in the corresponding end wall of thevulcanizer; Driven shaft 26 is rotated at desired speed by suitablepower mechanism indicated generally at 28 in Figure l. v

The reel 17 is designed to support a plurality of cylindrical mandrels30 in a manner to provide desired rotative movement to rubber tubingmaterial received thereon as the reel is rotated. Accordingly, said reelmay include axially spaced outer andinner disc-like end plates 31 and32, respectively, each having therethrough a plurality of radially andcircumferentially relatively closely spaced circularopenings 33, 33 and34, 34, of substantially larger diameter than the cross-section of themandrels (see'Figures 4 and 5), the lowermost edge portions of therespective aligned opening 33 and 34 being adapted to support protrudingends of the mandrels 30 having I tubing 35 supported thereon in a mannerto be described. The mandrels 30 may be retained against axial movementon the reel at the inner end thereof by a disc-like plate 36 fixed onthe shaft 18 in inwardly spaced relation to end plate 32 and by a plate37 mounted on theshaft,

18 to'be axially shiftable outwardly from and inwardly toward spacedrelation thereof to the outer end plate 31.

"31 (see chain-dotted lines at the right of Figure 4) the mandrels areaxially movable endwise to the right to release the opposite endsthereof from engagement through the openings 34 of inner plate 32,whereby the mandrels are readily removable from the reel. Insertion orloading of the mandrels in the reel is accomplished in converse manner,the loading and unloading operations,

of course, being accomplished while the unit 12 is outside thevulcanizer. I

In operation of the apparatus described for practicing the improvedmethod herein the unit 12, while located outside the vulcanizer 10 withthe retaining plate 37 in horizontal supporting position between thealigned openings 33 and 34 of end plates 31 and 32, respectively,

. these mandrels having supported thereon lengths of vuldrels may bethus positioned on the reel by inserting the right hand ends of the same(see Figure 4) endwise through the openings 33 of outer plates. 31 andthen moving mandrelsendwis'e to the left to insert the correspondingends thereof through the openings 34 of the inner end plate 32, afterwhich the retaining plate 37 is moved axially'inwardly on shaft 18 andturned in proper direction to lock it in retaining position, throughoperation of the bayonet connections 38.

When the loaded mandrels 30 are all in position, the unit 12 is movedinto the vulcanizer 10 until the clutch parts 24 and 25 are properlyengaged, and the door 11 of the vulcanizer is closed, after whichmechanism 28 is operated to rotate the reel 17, through driven shaft 26.The tubes 35 on the rotary reel are exposed to the usual vulcanizingheat of open steam, contained in the vuluniform vulcanization of therubber.

canizer at about 190 F., for about 12 minutes, after which the mechanism23 is stopped and the unit 12 is removed from vulcanizer id for removalof the mandrels 30 from the reel 17 as previously described.

The method of the invention will be best understood by reference toFigure 2, wherein a fixed point a is indicated on the inner periphery ofthe large opening 33 (or 34) of plate 31 (or 32). revolution the point awill also make a full revolution, as indicated by chain-dotted positionsof the opening 33. With each said revolution of point a the mandrel 30will make a number of revolution'sin clockwise direction,

When the reel makes a full whereby the tube 35 supported on the mandrelis fric tionally driven by the mandrel to rotate in clockwisedirection.In the proportions, shown in Figure 2 the rubber tube 35 would make atleast one revolution with each revolution of the reel 17, so that if thereel makes twelve upper portion of the mandrel, as shown.

Rotation of the tube 35 during vulcanization thereof prevents-scorchingof the rubber along the area of contact of the tube with the hot metalof mandrel 30. Moreover, such rotation prevents accumulation ofcondensate The diameter revolutions during a vulcanizing cycle, forexample, the 1 v 9 tube may also revolve about twelve times during thesame at the bottom of the tube which would adversely affect Theparticles of the rubber are uniformly aligned and the total result is atube of uniformly circular cross-section. Narrow elastic bands E, cutfrom this tube, in known manner, similarly will be of uniformly circularcross-section and of substantially uniform elasticity and tensilestrength. A finished elastic band B is shown in Figure 3.

Generally speaking the method herein contemplates rotation of anelongated tube of vulcanizable elastic material while supporting thesame by a portion .of its peripheral wall along its entire length, andat the same time exposing the tube to open heat of vulcanization.Satisfactory speeds for this purpose have been found to be between onehalf and five revolutions per minute. In the reel 17 shown in thedrawings the aligned openings 33 and 34 thereof may be, for example,approximately 2 /4 inches, while the mandrels used therewith may bewithin a range 1% to 2 inches in diameter, depending upon the size ofelastic bands to be made from the tubing. Rotation of the reel, andhence the mandrels, may be in alternately reversed directions to obviateany tendency toward twisting of the tubing.

Modifications of the invention may be resorted to without departing:from the spirit thereof or the scope of the appended claims.

What is claimed is:

1. A method of making elastic tubing as for production of elastic bands,comprising the steps of providing a length of thin-walled tubing, ofheat-curable, flexible elastic material, mounting said tubing on ahorizontally extending pportin mandr to usp n e y therefrom alon n areaof contact between the upper peripheral surface of the mandrel and theinner periphery of the tubing, and in the presence of open curing heatrotating the mandrel about its axis and thereby imparting rotativemovement to the tubing on the mandrel, said rotative movement of thetubing being for at least a part of the time in which the elasticmaterial becomes set during the curing cycle, whereby the particles ofthe elastic material are substantially uniformly aligned in the tubing,and whereby the cured tubing will have uniform tubular shape and uniformelasticity and, tensile strength;

2. A method of making elastic tubing as for production of elastic bands,comprising the steps of providing a length of thin-walled tubing, ofheat-curable, flexible elastic material, mounting said tubing on ahorizontally extending supporting mandrel to suspend freely therefromalong an area of contact between the upper peripheral surface of themandrel and the inner periphery of the tubing, and in the presence ofopen curing heat moving .the horizontally extending mandrel in an orbitwhile rotating the mandrel about its axis and thereby imparting rctativemovement to the tubing on the mandrel while moving in said orbit, saidrotative movement of the tubing being for .at least a part of the timein which the elastic material becomes set during the curing cycle,whereby the particles of the elastic material are substantiallyuniformly aligned in the tubing, and whereby the cured tubing will haveuniform tubular shape and uniform elasticity and tensile strength.

3. A method of making elastic tubing as for production of elastic bands,comprising the steps of providing a length of thin-walled cylindricaltubing of vuloanizable, flexible, rubber-like material, mounting saidtubing on a horizontally extending supporting mandrel to suspend freelytherefrom along an area of contact between the upperperipheral surfaceof the mandrel and the inner periphery of the tubing, and in thepresence of open heat of vuloanization moving the horizontally extendingmandrel about a continuous orbit whilesimultaneously rotating themandrel about its axis and thereby imparting rotative movement to thetubing on the mandrel, said rotative movement of the tubing being for atleast a part of the time in which the elastic material becomes setduring the vuloanizing cycle, whereby the particles of the elasticmaterial are substantially uniformly aligned in the tubing, and wherebysaid vulcanized tubing will have uniform cylindrical shape and uniformelasticity and tensile' strength. 7

4.;A method of as set forth in claim 1, wherein rota- 'tion of themandrel is periodically reversed to reverse th rotative movement of thetubing.

5. A method as set forth in claim 3, wherein movement of the mandrel is,periodically reversed to reverse the rotative movement of the tubing.

References Cited in the file of thispatent UNITED STATES PATENTS

